Glass fiber reinforced cement

ABSTRACT

Alkali resistant, fiberizable glass compositions are disclosed. These compositions contain TiO2, La203 or CeO2. The glass fibers formed from these compositions are useful in the reinforcement of cementitious materials.

United States Patent AU 115 H OR 3,902,912

Wolf 7 1 Sept. 2, 1975 [541 GLASS FIBER REINFORCED CEMENT 3.7810921/1974 Majumdar 106/99 3.852.082 12/1974 Majumdar.... 106/99 [75]Inventor 33" Reynoldsburg 3.861.925 1/1975 Wolf 106/50 [73] Assignee:Owens-Corning Fiberglas Corporation, Toledo, Ohi Primary Examiner-HelenM. McCarthy [22] Filed: May 2 19 4 Attorney. Agent, or FirmCarl G.Staelin; John W.

Appl. No.1 472,007

Related US. Application Data Division of Ser. No. 331.725, Feb. 12,1973, Pat. No. 3,861,925.

References Cited UNITED STATES PATENTS 5/1973 Chvalovsky ct a1 106/99Overman; Patrick P. Pacella 5 7 1 ABSTRACT tions are useful in thereinforcement of cementitious materials.

4 Claims, No Drawings GLASS FIBER REINFORCED CEMENT This is a divisionof application Ser. No. 331,725, filed Feb. 12. 1973 now U.S. Pat. No.3,861,925.

This invention relates to fiberizable glass compositions. Moreparticularly, this invention relates to glassfibers which are alkaliresistant.

Until quite recently it has not been advisable to use glass fibers forlong term (five or more years) reinforcement of cement, concrete, mortaror other cementitious materials or matrices that have a high alkalicontent. The harsh alkali environment would degrade the types of glassfibers, E glass for example, commonly used to reinforce non-alkalimaterials such as plastics.

E glass fibers are not generally recommended for the long termreinforcement of Portland cement or other cementitious products. Thealkali content of the cementitious matrix attacks the E glass fibersurface and substantially weakens the fibers. This alkali attack andsubsequent fiber strength loss generally so weakens the fibers that longterm reinforcement of the matrix by the E glass fibers is neitherpredictable nor dependable.

In order to provide glass fibers for the reinforcement of cementitiousproducts, alkali-resistant glass compositions containing zirconia havebeen developed. British'Pat. Specification No. 1,243,973 published onAug. 25, 1971 with A. J. Majumdar named as inventor describes alkaliresistant, fiberizable glass compositions containing ZrO in amountsranging from to percent by weight. British Pat. Specification No.1,290,528 published on Sept. 27, 1972 and assigned to PilkingtonBrothers, Limited, discloses an alkali resistant glass compositioncontaining, in molecular percentages, 7 to 11 percent of ZrO Anotheralkali resistant glass composition is disclosed in U.S. Pat. No.3,499,776, issued on Mar. 10, 1970. It describes a bulk glasscomposition, which may or may not be fiberizable, and that contains, inmole percent, ZrO in amounts ranging from 4 to 12 percent. Still anotheralkali resistant, fiberizable glass composition containing zirconia isdisclosed in U.S. Pan-application Ser. No. 275,613 filed on July 27,1972. The ZrO and TiO containing compositions described in ApplicationSer. No. 275,613 provide a unique combination of alkali-resistance, lowliquidus temperature and desirable viscosity for the fiberization ofglass compositions and for the reinforcement of cementitious materials.

Zirconia free glass compositions which are resistant to alkali attacknow have been discovered. In the glass compositions and glass fibers ofthis invention, Zirconia has been replaced with titania (TiO lanthana(1.21 0 or ceric oxide (CeO Accordingly, an object of this invention isto provide fiberizable glass compositions.

Another object is to provide alkali resistant glass fibers.

Still another object is to provide a reinforced cementitious product.

Other objects, aspects and advantages of the invention will be apparentto one skilled in the art from the following disclosure and appendedclaims.

The glass compositions of this invention fall within the following rangeof proportions:

It has been discovered that glass compositions falling within this rangeof proportions can be formed into fibers using commercial E glassmelting and fiber forming techniques and at commercial E glassproduction rates. Also it has been found that glasses of this type willhave a liquidus temperature so low, less than 1500F in somecompositions, that devitrification of the molten glass prior to orduring fiber forming can be ignored. This is a significant processingadvantage in that devitrification can lead to costly and time consumingproduction shut downs.

As previously discussed, the prior art has developed alkali resistantglass compositions. Some of the best ones developed to date contain Zr0in combination with TiO The compositions of this invention contain TiOLa O or CeO and free of Zirconia.

Commercial fiber forming processes are geared to melt the glasscompositions at about 2650 to 2750F and fiberize it at about 2250 to25001 To avoid devitrification of the molten glass in the melting orfiberizing zone it is important that the liquidus or devitrificationtemperature of a glass be at least F, and preferably E or more, belowthe usual fiberizing temperature. Using the glasses of this inventiondevitrification problems are virtually eliminated.

The other key property of smooth running, commercial, fiber formingglasses is viscosity. Viscosities of 10 poises at temperatures of 245OFor less and 10 3 poises of 2220F or less are most desirable. The glasscompositions of this invention easily meet this requirement.

Specific glass compositions embodying the principles Ingredient Example1 Example 11 Example 111 Weight Percent Mole Percent Weight Percent MolePercent Weight Percent Mole Percent 510 63.8 66.6 56.7 66.6 61.3 69.2TiO, 13.2 10.4 La o: 22.8 10.4 CeO, 16.4 6.3 CaO 5.4 6.0 4.8 6.0 5.0 6.0Na,O 15.0 -15.2 13.4 15.2 16.9 18.5 K,O 2.6 1.8 2.4 1.8

Liquidus: Temp.. F Less than 1500 2120 2075 Viscosity; Temp. F

L11 Log Poise -continued Ingredient Example I Example ll Example IllWeight Percent Mole Percent Weight Percent Mole Percent Weight PercentMole Percent The viscosity determinations in Examples I to Ill-continued were obtained using the apparatus and procedure de- 10lngmdicm weight hm"t scribed in US. Pat. No. 3,056,283 and in an articlein R O (H o) x 2 LI; l) The Journal of the American Ceramic Society,Vol. 42, no: & H.203 0 m I No. 11, November, I959, pages 537-541. Thearticle is entitled Improved Apparatus for Rapid Measurement Table ITensile Strength Retention of E Class Environment Immersion TimeSolution Temp. '14 Strength Retained Air Cement Solution Cement SolutionCement Solution Cement Solution Cement Solution Table 2 Tensile StrengthRetention of Glass of Example I Environment Immersion Time SolutionTemp. 1 Strength Retained Air Cement Solution of Viscosity of Glass atHigh Temperatures" by Ralph L. Tiede.- Other specific viscositydeterminations referred to herein also would be measured by theapparatus and procedure in the Tiede article.

In the glass compositions of this invention SiO is the primary glassforming ingredient. The alkali metal oxides Na O and K 0 are used tocontrol viscosity. CaO is used primarily to control liquidus. It doesthis without adversely affecting the viscosity.

TiO La O or CeO is the ingredient believed to be responsible for thealkali resistance of these glasses.

Fe O and N 0 can enter these glass compositions as impurities of thebatch raw materials. Preferably Fe O should be maintained below about0.5 percent by weight and AI O should be maintained below about 1percent by weight.

EXAMPLE IV Ingredient Weight Percent SiO, 54 to 55 M 0, 14 to 15 R0 (caO& MgO) 22 B 0; 6 to 8 F, 0.5 to l The procedure for obtaining thestrength retention values of Tables I and 2 was essentially as follows.Each of the glass compositions was fiberized and coated with the sameforming size. Fiber diameter was maintained in the range of 50 to 55hundred thousandths of an inch. All strands had 52 filaments.

Strands of each glass were wound around and suspended between brass pegsspaced about 1 foot apart. These pegs and strands were then immersed ina synthetic cement solution having a pH of 12.4 to 12.5 and comprisingan aqueous solution of 0.88 grams/liter of NaOH, 3.45 grams/liter of KOHand 0.48 grams/liter of Ca(OH) This cement solution is described inBritish Majumdar Pat. specification No. l,243,073 and in an article byA. J. Majumdar and .I. F. Ryder entitled "Glass Fibre Reinforcement ofCement Products appearing at pages 78-84 of Glass Technology, Vol. 9(3), June, 1968.

Polypropylene pans containing the solutions and immersed samples werecovered and placed in ovens maintained at a temperature of I48F for theindicated periods of time.

At the end of each time period. for example 1 week, the samples wereremoved from the cement solution, rinsed in tap water and dried in air.The samples in Tables I and 2 tested in an air" environment were notimmersed in the cement solution but exposed only to air, rinsed in tapwater and dried in air.

After air drying of the samples their tensile strength was measured on afloor model Instron Universal testing machine, Model TTC. serial number1680 at a gage length of 2.0 inches and a strain rate of 0.1 inch/inch-/minute. For each time interval at least twenty strands of each glasswere broken. The percentage of the strength retained by each glass inTables I and 2 therefore represents an average of at least twentytensile hours at a pressure of 225 p.s.i. and at a temperature ofstrength readings. 190C. The molded product is allowed to cool and canComparing the strength of E glass with the strength be dried byconventional means if necessary. The of the glas f Ex mpl I l y showsthe superior lmolded product will be found to be indurated in its kaliresistance of the Table 2 glass. The high degree of 5 i i l i d h alkaliresistance combined with the favorable fiberizing M difi ti d variationsi hi h Scope f [he and liquidus temperatures, and liquidus-viscosityrelaattached claims are i d d be i l tionship of the glasses of thisinvention make them lclaim;

highly desirable. Their fiber forming characteristics make them as easyto work with as E glass, while their alkali resistance makes themsuitable for reinforcing cemetitious matrices.

l. A cementitious product comprising a composite of reinforcingmaterials and a calcium silicate cementitious matrix wherein one of saidreinforcing materials comprises alkali-resistant, zirconia free glassfibers. EXAMPLE v said glass fibers consisting essentially of:

Glass fibers embodying the principles of this inven- M l P l tron alsohave been incorporated in other kinds of ce- 0 e mentitious products ormatrices including cement, coni z 65 to 70 crete and mortar. Thesefibers have resisted alkali at- C80 2:; tack and reinforced theproducts. Cemetitious products Na O 14 to 20 R 0 0 to 3 also have beenmade which are reinforced wy glass i.bers g 1his i nvention incombination with other rein .foncingmaterialssufia'sfigsfggfibejlsfgfwo'o l ers.

For example, a calc fiim silicate insulating" wherein X is TiO La O orCeO having a matrix of a tobermorite crystalline structure TheFemenmlOQSP of claim 1 wherein Said can be prepared by initially forming a slurryhaving a cememmous matrix 15 rtland C ment. water to solids ratio ofabout 5.5 and a molar ratio of The cementitious pro ct of Claim 1wherein said CaO to SiO of about 0.8. The solids contained aboutcementitious matrix is concrete. -20 parts by weight of glass fiberstrands of the glass of 4. The cementitious product of claim 1 whereinsaid Example I. The resultant slurry is indurated in an atmocementitiousmatrix is mortar. sphere of superheated steam for a period of about 6.5

1. A CEMENTITIOUS PROUCT COMPRISING A COMPOSITE OF REINFORCING MATERIALSAND A CALCIUM SILICATE CEMENTITIOUS MATRIX WHEREIN ONE OF SAIDREINFORCING MATERIALS COMPRISES ALKALIRESISTANT, ZIRCONIA FREE GLASSFIBERS, SAID GLASS FIBES CONSISTING ESSNTIALLY OF:
 2. The cementitiousproduct of claim 1 wherein said cementitious matrix is Portland cement.3. The cementitious product of claim 1 wherein said cementitious matrixis concrete.
 4. The cementitious product of claim 1 wherein saidcementitious matrix is mortar.